Reclaiming of oil is receiving new emphasis, spurred in large part by the energy crisis and the increased cost of virgin oil. New technologies in reclaiming used oil are being explored. A highlighted survey of the field is given in Science, Vol. 193, No. 4258, pp. 1108-1110, Sept. 17, 1976, published by the American Association for the Advancement of Science.
However, the safe disposal of the unusable components in the reclaiming process, commonly referred to as sludge, remains a serious problem. Past practices of dumping the sludge into waterways and landfill areas have seriously polluted the environment and have posed health hazards to the people directly involved with transporting the sludge. Moreover, it has been recognized that not only are the gross contaminants, acid, fumes, etc., an environmental hazard, but also the release of some ingredients measured in parts per million must be avoided for the protection of the environment. Notable among the minutely present ingredients are the polyhalogenated biphenyls and particularly the polychlorinated biphenyls. Polychlorinated biphenyls, most commonly found in oils used for heat transfer properties, have only recently been recognized as serious pollutants and safe disposal practices must immobilize the polyhalogenated biphenyls and prevent their entry into the environment.
Old conventional oil reclaiming and re-refining processes have typically involved the use of distillation, followed by acid treatment to produce acid sludges (waste) and then clay treatment of the desludged oil. This clay treatment has been typically carried out by naturally bleaching earths such as montmorillonites or attapulgites as produced by Englhard Minerals & Chemicals Co. and the ITT-Floridian Co., and/or with acid-activated bleaching clays as produced typically by Filtrol Co. and Morton Chemical Co.
This process typically may involve percolation filtration using a granular bed of bleaching clay of a size ranging from 6 mesh to 200 mesh but more commonly in the range of -24 mesh to +60 mesh wherein the material to be processed is passed into this fixed bed to obtain the desired results. Alternatively, the contact filtration process is used wherein finely ground and/or air-classified powdered bleaching clay is mixed in typical ratios of 1% to 4% bleaching clay to oil by weight. After agitation, with possible additions of heat over a period of typically 5-20 minutes, this slurry is subsequently passed through filter presses to separate the bleaching clay from the refined oil. This practice is not the same as the present invention. The solid sludge-clay product of the invention is not to be confused with sludge-filters or sludge-clay tailing which contain insufficient clay and are not admixtures. Practitioners in the art of reclaiming oil recognize that clay and acid treatments produce acid sludges and clay sludges which, along with PCB contaminated oils, are difficult to dispose of without creating pollution. This is emphasized in recent U.S. Pat. Nos. 3,625,881 and 4,033,859.
The reclaimed oil and rejected sludge is generally recycled from automotive crankcase oil drainings from internal combustion engines or electric transformers. The oil before reclaiming has many additives such as viscosity index improvers, rust inhibitors, and the like. Decomposed products of such additives and other contaminants such as dirt, foreign metallic particles and carbonaceous matter find their way into the oil. An extensive list of ingredients in oil is given in U.S. Pat. No. 3,919,075. Polychlorinated biphenyls, commonly found as an additive to transformer oils, are particularly serious ingredients in view of the high toxicity per minute quantity. The polychlorinated biphenyls are used generally to enhance the dielectric properties and thermal transfer characteristics of the oil in electric transformers and other associated equipment. One such additive is marketed by Dow Chemical Company under the name DOW-THERM.
Therefore, it remains a serious problem in industry to contain complementary additives and the impurities removed from oil in a manner that is environmentally safe. Heretofore, storage disposal means have not contained the sludge in a safe manner. Commonly, the sludge or PCB contaminated oil has been dumped into holding ponds or landfill areas where the acids, metals, polychlorinated biphenyls, and other impurities can leach into groundwater, float out of the storage area, or be washed into streams with rain and runoff water. Attempts to stabilize the waste with sawdust, peanut hulls, or straw have not been successful for the absorbents do not contain the sludge and are susceptible to floating out of storage areas. These absorbents are also organic in nature and tend to decompose, thus losing their absorbency.
Therefore, it is an object of the present invention to provide a process for the environmentally safe disposal of acid sludges from oil reclaiming processes.
Another object is to provide a process for environmentally safe disposal of any aqueous or non-aqueous sludge from oil reclaiming processes.
Still another object is to provide a process for the environmentally safe disposal of sludge or contaminated oil which renders the sludge or oil immobile in sanitary landfills.
Yet another object of the present invention is to provide an environmentally safe disposal of oil which contains polychlorinated biphenyls.
Still another object of the invention is to provide a sludge or oil containing solid which reduces the risk of health hazard to the workers transporting the solid.
Additional objects and advantages of the present invention will be apparent to those skilled in the art by reference to the following detailed description.